US 7373801 B2
A test fixture for rollover crash testing of a test vehicle onto a moving surface employs a cradle to support and rotate the test vehicle. A vertical support structure to positions and releasably holds the cradle. A moving sled having a contact surface is carried by a guide extending beneath the structure and the cradle fixture. The cradle is rotated and released from the structure responsive to a sensor for contact within a drop impact zone on the contact surface of the moving sled. Vertical motion of the cradle is then arrested to prevent further damage to the test vehicle or the test structure.
1. A test fixture for rollover crash testing of a test vehicle onto a moving surface said fixture comprising:
a cradle to support and rotate a test vehicle;
a structure to position and releasably hold the cradle;
a moving sled having a contact surface and carried by a guide extending beneath the structure and the cradle;
means for releasing the cradle and test vehicle from the structure responsive to a sensing means for contact within a drop impact zone on the contact surface of the moving sled;
means for rotating the cradle; and
means for arresting vertical motion of the cradle.
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17. A method for crash testing of a test vehicle or representation thereof onto a moving surface comprising the steps of:
providing a structure to support and position a test vehicle component above a moving sled path;
providing a moving sled on the path onto which the test vehicle is dropped in synchronous coordination with simulated roadway obstacles within an impact zone;
rotating the support structure to position the test vehicle for impact onto the impact zone on the moving sled;
triggering the drop of the test vehicle at a specific time with respect to the position of the moving sled; and, isolating the test vehicle from additional impacts after the desired impact or impacts as the moving roadway proceeds beyond the impact zone after impact.
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This application claims the priority of U.S. Provisional Patent Application Ser. No. 60/676,160 filed on Apr. 29, 2005 having the same title as the present application.
1. Field of Invention
This invention relates to an automotive vehicle test fixture. In particular, the invention relates specifically to a fixture to conduct dynamic, repeatable, controlled destructive rollover impact tests of both full scale vehicles and representations to evaluate strength characteristics of the vehicle roof and other vehicle components. The invention provides precise control of initial test parameters including drop height, contact roll rate, contact roll angle, pitch angle, yaw angle, roadway speed, post contact freefall height, vehicle moment of inertia, roadway surface conditions including friction and impact obstructions. In addition, the invention enables multiple tests to be conducted and evaluated on an isolated singular roll-by-roll basis.
2. Description of Prior Art
Rollovers have been and continue to be a significant cause of occupant fatalities and serious injuries. To date, the experiments to determine vehicle performance have been criticized as unrepeatable and, thus, inappropriate for vehicle or component design and testing and/or compliance type testing. Various other test fixtures been developed that addresses some of these issues, but requires a large infrastructure to run and does not fully control the vehicle during the test (reference: U.S. Pat. No. 6,651,482). Another device (reference U.S. Pat. No. 6,256,601) articulates about a pivot but does not provide a full rollover capability, nor does it provide a means to simulate a roll about the true roll axis of a vehicle. In addition, none of the other test methods allow for the direct measurement of the loads applied to the vehicle, which are important to evaluating and understanding the dynamics of a rollover event. This subject invention resolves these issues in a manner that will allow effective repeatable vehicle testing. Vehicle testing in the rollover regime is crucial to understanding interactions between the occupant and the vehicle's structures, restraints, glazing, etc. A better knowledge of these parameters will allow for improved vehicle designs and a safer vehicle fleet.
Previous testing to determine vehicle performance and vehicle to occupant interactions in rollover conditions uses various types of tests including dropping a rotating vehicle, launching a vehicle from a dolly, launching a vehicle from a ramp or otherwise tripping a vehicle to initiate a roll. The major drawback of these tests is the unrepeatable nature of the testing. While these tests will allow insight into vehicle performance, they do not allow a study of vehicle and component performance during an impact that can be exactly repeated to determine changes in vehicle structure or geometry through repeated tests. In particular, earlier test methods do not result in consistent impacts due to variations in tire to dolly or tire to road impacts before the roof structure interaction or are not controlled after the roof impacts. By controlling the vehicle both before and after the roof impacts, performance during an impact can be isolated and examined in detail.
U.S. Pat. No. 6,651,482 describes an alternate method of rollover testing. The method described in that patent is considerably different from the invention discussed herein. These differences lead to several shortcomings in the previous methodology including the inability to measure the direct forces on the roof of the vehicle, the inability to control the vehicle after the desired roof contacts, the artificial positioning of anthropomorphic crash test dummies if included, the inability of the system to directly determine the roof crush from the desired impact, the inability to evaluate damage on a per roll basis.
U.S. Pat. No. 6,256,601 describes a rollover test sled designed to simulate the behavior of vehicle occupant and safety systems in a rollover accident. The method described differs significantly from the invention presented herein since the test does not provide the means to rotate a test vehicle or dummies about a roll axis. The fixture described also does not provide the means to rotate the test vehicle for the purposes to measure and evaluate vehicle structural integrity.
This invention addresses these issues and provides an improved dynamic, repeatable vehicle rollover test fixture.
A test fixture for rollover crash testing of a test vehicle onto a moving surface incorporates a cradle to support and rotate a test vehicle. The cradle is carried by a structure to position and releasably hold the cradle. A moving sled having a contact surface simulating a roadway is carried by a guide extending beneath the structure and the cradle fixture. The cradle and supported vehicle is released from the structure responsive to a sensor for contact within a drop impact zone on the contact surface of the moving sled. The cradle is rotated to coordinate the test vehicle and roadway position at impact and the vertical motion of the cradle is arrested at the event completion to avoid damage to the track and sled system as well as limiting further damage to the test vehicle.
The elements and features of the invention are further described with respect to the detailed description herein and the following drawings wherein
An exemplary embodiment of the present invention is illustrated in
The drop towers assembly 120 includes a front drop tower 122 and a rear drop tower 123 connected overhead by a tower connection beam 121. The drop tower assembly 120 straddles the sled guide rails 115 and the towers are mounted to the yaw adjustment guide plates 119 that are pivotably fastened to the floor 101, as best seen in
With the moving sled simulating the roadway for impact of the vehicle, rotation of the vehicle cradle synchronizes the impact of the vertically descending vehicle with the horizontally moving roadway. A rotation drive assembly 140 located adjacent the front drop tower 120 provides a rotation drive pulley support frame that supports a rotation drive pulley 142. A rotation drive support shaft 143 couples the rotation drive pulley 142 and the vehicle cradle 131. The drive support shaft 143 incorporates universal joints 106 that provide angular alignment between the drive pulley 142 and the vehicle cradle 131. Slide rods 109 couple the vehicle cradle to the runner assemblies.
For the embodiment shown in the drawings, motion of the sled is provided by a propulsion assembly 150, best seen in
The first end of coupling cable 139 attaches to the trailing side of the sled 110 with the second end spooled about the coupling pulley 138. The coupling pulley 138 is mounted and affixed onto a synchronization pulley 137 that rotates about a bearing shaft. A first end of a rotation drive cable 144 is spooled about the synchronization pulley 137 while the second end of the rotation drive cable 144 is spooled about the rotation drive pulley 142 as guided by a rotation idle pulley 145.
A sled decelerator 170 located at the end of the sled guide rails 115 is provided to beneficially decelerate and stop the sled in a controlled manner at the end of its travel. A drop trigger switch 117 located between the sled guide rails 115 and ahead of the drop towers 120 is provided to detect the leading edge of the sled 130 as it translates forward. Upon actuation of the trigger switch, the front drop actuator 126 and the rear drop actuator 127 are enabled thereby releasing the runners supporting the vehicle cradle 131 for motion down the vertical guide bearings 130 to synchronously drop with respect to the position of the sled 110.
At the completion of the roll-over impact event, the car body or buck must be arrested to prevent damage to the support elements of the fixture or the sled or drive system through unwanted contact after the roadway portion on the sled has passed. To accommodate this requirement, a vertical brake assembly 107, best seen in
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Having now described the invention in detail as required by the patent statutes, those skilled in the art will recognize modifications and substitutions to the specific embodiments disclosed herein. Such modifications are within the scope and intent of the present invention as defined in the following claims.